Spring planting decisions

By James Hoorman, Hoorman Soil Health Services

Last year, spring planting occurred during a cold dry spring, while this year conditions are warm and dry. Farmers have several planting options, depending on whether they are conventional tillage farmers or planting no-till with cover crops. What options farmers choose and their success may depend upon soil and moisture planting conditions.

First, the wheat crop is really green and uniform this year in Northwest Ohio. February snows protected the wheat from cold temperatures and most wheat did not drown out. Microbial levels are generally low after winter and start building as temperatures rise. The soil is a grave yard of dead microbial bodies which have abundant nutrients. During excessive snow melt and heavy spring rains, many soluble nutrients wash away. The dry spring kept soil nutrients around and plants are absorbing these abundant nutrients, promoting lush green plants.

Conventional tillage farmers may be tempted to do more spring tillage, but each tillage pass reduces soil moisture by 0.5-1.0 inch. Removing soil moisture warms up soil faster and promotes faster germination. This year, the extra tillage may excessively dry the soil and may or may not be detrimental. Farmers generally do more tillage in the fall when temperatures and moisture are lower and soil compaction is minimized allowing soil to fracture over winter. Spring tillage when soils are wet promotes soil compaction but spring tillage in a dry year may excessively dry out a soil.

In dry years, farmers are advised to plant crops deeper to get enough moisture for germination. Planting deeper creates a healthier plant that can root deeper and reduces lodging potential. However, if a farmer has poor soil structure, any rain and heat may cause the soil to seal over and crust, and may hurt plant emergence. Good soil structure comes from having high soil organic matter levels and live roots to provide the glues and sugars needed to make soils more friable. No-till farmers and cover crops should have better soil structure over time and have less problems with planting deep or with emergence problems. Conventional farmers who tilled last fall often plant directly into a “stale seed bed” in the spring. If it stays dry this spring, it may be advantageous to minimize or eliminate surface tillage this year.

No-till farmers also have several decisions to make, especially if they planted cover crops. In wet years, green growing cover crops are good for transpiration and drying out soils while reducing weed pressure. Depending upon how dry it is, farmers can terminate cover crops early (2-3 weeks before planting), at planting, or plant green and terminate after crops germinate or

emerge. Many farmers want to avoid planting issues, so they terminate cover crops early. This year, if it stays dry, that may be a good strategy to conserve moisture. Generally, killing cover crops at planting is almost always a bad decision. These cover crops tend to bind and wrap because the residue may not be totally dead or dry. In rye, the allelopathic effect comes from the leaves and the stems which leach a natural herbicide that can hurt corn but not soybeans. Planting green is a good option unless the soil and weather conditions get too dry, then killing early may be better.

Planting green has several advantages and disadvantages. Planting green allows plants to dry out soil, reduces weed pressure, reduces frost damage, and is easier to plant into because green plants slide through the planter. Planting soybean green is much easier than planting corn green. Decomposing plant residues tend to tie up nitrogen, so add 40-70# of actual nitrogen (N) in corn starter fertilizer to reduce N tie up. Green covers can be terminated with a crimper crop roller which forms a mulch to protect soil from soil erosion, reduces weed pressure while saving a herbicide application, improves water infiltration, keeps soils cooler in the summer, and conserves soil moisture during a dry summer.

Disadvantages of planting green are excessive spring moisture reduction which may promote a harder denser soils, nitrogen tie up, and sometimes more insect pressure from army worms and other pests. Most insect pests can be kept in check once natural predator levels are reestablished. Sometimes a rescue treatment may be required to save the crop but most insecticides kill everything (good and bad). Farmers have a lot of timely decisions to make this year and hopefully this discussion helps you make the right decision for your farm.

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